Fixes performance issue with HighestSequenceNrSql query (#5420)

Co-authored-by: Aaron Stannard <aaron@petabridge.com>
akkadotnet · Dec 8, 2021 · c1b0924 · c1b0924
1 parent 1382b3c
commit c1b0924
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/src/contrib/persistence/Akka.Persistence.Sql.Common/Journal/BatchingSqlJournal.cs b/src/contrib/persistence/Akka.Persistence.Sql.Common/Journal/BatchingSqlJournal.cs
@@ -622,9 +622,9 @@ protected BatchingSqlJournal(BatchingSqlJournalSetup setup)
             HighestSequenceNrSql = $@"
                 SELECT MAX(u.SeqNr) as SequenceNr 
                 FROM (
-                    SELECT e.{conventions.SequenceNrColumnName} as SeqNr FROM {conventions.FullJournalTableName} e WHERE e.{conventions.PersistenceIdColumnName} = @PersistenceId
+                    SELECT MAX(e.{conventions.SequenceNrColumnName}) as SeqNr FROM {conventions.FullJournalTableName} e WHERE e.{conventions.PersistenceIdColumnName} = @PersistenceId
                     UNION
-                    SELECT m.{conventions.SequenceNrColumnName} as SeqNr FROM {conventions.FullMetaTableName} m WHERE m.{conventions.PersistenceIdColumnName} = @PersistenceId) as u";
+                    SELECT MAX(m.{conventions.SequenceNrColumnName}) as SeqNr FROM {conventions.FullMetaTableName} m WHERE m.{conventions.PersistenceIdColumnName} = @PersistenceId) as u";
 
             DeleteBatchSql = $@"
                 DELETE FROM {conventions.FullJournalTableName}

diff --git a/src/contrib/persistence/Akka.Persistence.Sql.Common/Journal/QueryExecutor.cs b/src/contrib/persistence/Akka.Persistence.Sql.Common/Journal/QueryExecutor.cs
@@ -343,9 +343,9 @@ protected AbstractQueryExecutor(QueryConfiguration configuration, Akka.Serializa
             HighestSequenceNrSql = $@"
                 SELECT MAX(u.SeqNr) as SequenceNr 
                 FROM (
-                    SELECT e.{Configuration.SequenceNrColumnName} as SeqNr FROM {Configuration.FullJournalTableName} e WHERE e.{Configuration.PersistenceIdColumnName} = @PersistenceId
+                    SELECT MAX(e.{Configuration.SequenceNrColumnName}) as SeqNr FROM {Configuration.FullJournalTableName} e WHERE e.{Configuration.PersistenceIdColumnName} = @PersistenceId
                     UNION
-                    SELECT m.{Configuration.SequenceNrColumnName} as SeqNr FROM {Configuration.FullMetaTableName} m WHERE m.{Configuration.PersistenceIdColumnName} = @PersistenceId) as u";
+                    SELECT MAX(m.{Configuration.SequenceNrColumnName}) as SeqNr FROM {Configuration.FullMetaTableName} m WHERE m.{Configuration.PersistenceIdColumnName} = @PersistenceId) as u";
 
             DeleteBatchSql = $@"
                 DELETE FROM {Configuration.FullJournalTableName}